1. Technical Field
This invention relates generally to diesel engine fuel control systems and more particularly to diesel engine fuel control systems adapted to reduce dead-pedal effects.
2. Background
As is known in the art, diesel engines operate at idle with idle fuel supplied from an idle speed fuel controller. When the operator wishes to accelerate a vehicle having a diesel engine from idle, he or she actuates an acceleration device, such as a foot pedal, typically referred to as an accelerator pedal. Thus, referring to FIG. 1, at idle, i.e., when the engine is in idle with the pedal position is at zero degrees, (i.e., the operator removes his or her foot from the accelerator pedal), the engine is supplied an amount of fuel from the idle speed fuel controller sufficient to maintain idle. The required idle fuel amount takes into consideration such things as accessory load, transmission load, etc. The amount of fuel supplied by the idle speed fuel controller is shown in FIG. 1.
Also shown in FIG. 1 is the amount of fuel demanded from acceleration pedal position depression, i.e., pedal position demanded fuel when the operator wishes to move the vehicle from its idle position. Thus, in FIG. 1, prior to time T1 the engine is in idle and the pedal is the zero degree position. The pedal is depressed beginning at time T1 and here, for example, increases somewhat linearly. It is noted that the amount of fuel actually supplied to the engine will be the greater of: (1) the required idle fuel supplied by the idle speed fuel controller; and (2) the pedal position demanded fuel. Thus, it is noted that until the pedal position demanded fuel exceeds the idle fuel supplied by the idle speed fuel controller, here at time T2, the fuel actually supplied to the engine is that from the idle speed fuel controller. Thus, there is no response of the engine to the pedal action of the operator between time T1 and time T2. This non-responsiveness of the engine to the operator demand is referred to as “dead pedal” delay. This dead pedal “delay” reduces the “performance-feel” of the vehicle to the operator.